World number one Rory McIlroy has stepped up his preparations for the defence of his US PGA Championship title with a practice round at Whistling Straits.

McIlroy has yet to say publicly if he will contest the year's final major, but gave numerous hints on social media this week and on Friday was paired with Jordan Spieth and Zach Johnson for the first two rounds next Thursday and Friday.

And on Saturday the four-time major winner was pictured on the course where he finished a shot outside the play-off between Martin Kaymer and Bubba Watson in 2010 as he looks to make a quicker-than-expected return to action.

McIlroy suffered a "total rupture" of ligaments in his left ankle during a game of football with friends on July 4, ruling him out of the Scottish Open and the defence of his Open and WGC-Bridgestone Invitational titles.

The 26-year-old's last competitive round was a closing 66 in the US Open at Chambers Bay on June 21. The US PGA gets under way on August 13.

McIlroy will be replaced as world number one by Masters and US Open champion Spieth if the 22-year-old American can win his first World Golf Championship title at Firestone Country Club on Sunday.

It was at the same event that McIlroy overturned a three-shot deficit to Ryder Cup team-mate Sergio Garcia in the final round 12 months ago to move back to the top of the rankings.

After completing his round alongside friend Harry Diamond, McIlroy posted a picture on Twitter of himself on the 18th tee, writing: "Great 18 holes this morning with haza136 @ Whistling Straits Golf Club."

Todd Lewis of the Golf Channel reported that McIlroy had told him that made for a total of 90 holes of golf since his injury, with James Haddock of Sky Sports News quoting McIlroy as saying his ankle was "feeling fine".